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101.
No increase in numbers of fungi, actinomycetes and bacteria in 3 days, as measured by selective media, was used as an indication of the presence of fungistasis, actinostasis and bacteriostasis in soil, respectively. The population of fungi, actinomycetes and bacteria did not increase in 9 of 10 soils tested indicating concurrent existence of fungistasis, actinostasis and bacteriostasis in a wide range of soils. When Penicillium funiculosum, Streptomyces scabies and Agrobacterium radiobacter were used as test organisms, these three types of microbiostasis were detected simultaneously in all 8 soils tested. All three groups of microorganisms flourished in autoclaved soil, and microbiostasis was restored to sterilized soil by reinoculation with 1% natural soil or microorganisms including antibiotic and non-antibiotic producers. Soil microbiostasis was annulled completely or partially by addition of different nutrie0nts. Bacteriostasis appeared to be the easiest to overcome with nutrients among these three types of microbiostasis. 相似文献
102.
Silsesquiazane (SSQZ), one of the branched forms of polysilazane, was blended with polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(iso-butyl methacrylate) (PBMA), and poly(vinyl acetate) (PVAc) to produce organic-inorganic hybrid materials. The polymers were selected to provide specific interaction, such as ??-?? interaction or hydrogen bonding, with SSQZ. AFM studies revealed that carbonyl containing polymers, PMMA, PBMA, and PVAc were miscible with SSQZ while PS was immiscible. DSC analysis of the hybrids also supported the miscibility behaviours of the system. The glass transition behaviour of SSQZ/PS showed individual transition temperature corresponding to the each component while SSQZ/carbonyl-containing polymers displayed one transition temperature that matched with the theoretically calculated values following the Kwei equation. Among the miscible hybrid system, the interaction with SSQZ increased in the order of PMMA> PBMA> PVAc, as determined by the q value in the Kwei equation. This result was confirmed by determining the degree of hydrogen bonding in FT-IR spectra. Thermal stability of organic polymers was improved by incorporating SSQZ regardless of the miscibility. 相似文献
103.
Muzafar A. Kanjwal Nasser A. M. Barakat Faheem A. Sheikh Woo-il Baek Myung Seob Khil Hak Yong Kim 《Fibers and Polymers》2010,11(5):700-709
As titanium oxide is a well-known photocatalyst, we investigated the effects of silver content and nanostructural morphology
on the photocatalytic degradation of two dyes, methylene blue and rhodamine B. Two nano-formulations were utilized, including
nanofibers and nanoparticles. Silver-grafted titanium oxide nanofibers were synthesized using the electrospinning of silver
nitrate/titanium isopropoxide/poly(vinyl acetate) sol-gel. The nanoparticulate form was obtained by calcination of a ground
powder prepared from the same electrospun sol-gel. The results affirmed the advantage of the silver-grafted titanium oxide
nanostructures over the silver-free ones. Increasing the silver content in the nanofibers led to increases in their surface
area, which is an important parameter in heterogeneous catalytic chemical reactions. Therefore, the results strongly suggest
the use of silver-grafted titanium oxide in a nanofibrous form. These results further support utilizing Agloaded titanium
oxide nanofibers as a photocatalyst. 相似文献
104.
Solid-state polymerization of poly(trimethylene terephthalate)(PTT) was carried out to obtain high molecular weight polymers.
Two kinds of commercial PTT chips were polymerized in the solid state by the heat treatment at 190∼220°C for various times
and they were characterized by end group content, molecular weight, thermal analysis, and X-ray diffraction. In the solid-state
polymerization of PTT, the overall reaction rate was governed by the solid-state polymerization temperature and time, and
pellet size. The content of carboxyl end groups decreased during the solid-state polymerization with increasing solid-state
polymerization temperature and time. The melting temperature and crystallinity of the PTT were higher for the ones treated
at higher temperature and longer time. The activation energy for the solid-state polymerization of PTT was in the range of
24∼25 kcal/mol for both chips. Through the solid-state polymerization of commercial PTT chips, high molecular weight polymers
up to an intrinsic viscosity of 1.63 dl/g was obtained, which corresponded to about a 117,000 weight-average molecular weight. 相似文献
105.
Kwang Ho Sohn Min Kwan Kim So Min Lee Byung Chul Ji Kwang Soo Cho Kyungmoon Jeon Han Do Ghim 《Fibers and Polymers》2011,12(4):451-456
Triphenyl phosphate (TPP) is well known to be one of the most effective flame retardants for acrylonitrile-butadiene-styrene
copolymer (ABS) and its blending resins, such as polycarbonate (PC)/ABS, among various phosphorous-based compounds. However,
TPP can also play a role as a plasticizer, which decreases the mechanical properties of PC/ABS resins at high temperature.
Furthermore considerable amount of TPP has to be evaporated during molding process due on its much lower evaporation temperature.
To overcome these shortcomings, we tried to immobilize TPP by grafting on butadiene moiety of ABS. FT-IR analysis of prepared
TPP-grafted ABS (ABS-g-TPP) comparing with TPP, ABS and their blend confirmed that chemical reactions happened between TPP
and ABS resins and it was attributed to the graft reaction of TPP onto butadiene moieties. Prepared ABS-g-TPP resins were
blended with PC at various compositions to be prepared as testing specimens by injection molding. The physical characteristics
such as mechanical properties, thermal stability, and flame retarding properties of the PC/ABS-TPP graft copolymer were analyzed
through Vicat softening temperature, IZOD impact strength, transmission electron microscope, and UL94 flame retardation tests.
Results showed that PC/ABS-g-TPP resin takes better thermomechanical properties than the existing PC/ABS resins at relatively
low additional TPP amounts. 相似文献
106.
Ho Cheon Lee Young Gyu Jeong Byung Gil Min Won Seok Lyoo Sang Cheol Lee 《Fibers and Polymers》2009,10(5):636-642
We prepared a series of polyurethane(PU)/chitosan composite foams with different chitosan content of 5∼20 wt% and investigated
their adsorption performance of acid dye (Acid Violet 48) in aqueous solutions with various dye concentrations and pH values.
It was observed that PU/chitosan composite foams exhibited well-developed open cell structures. Dye adsorption capacities
of the composite foams increased with the increment of chitosan content in composite foams, because amine groups of chitosan
serve as the binding sites for sulfonic ions of acid dyes in aqueous solutions. In addition, dye adsorption capacities of
composite foams were found to increase with decreasing the pH value, which stems from the fact that the enhanced chemisorption
between protonated amine groups of chitosan and sulfonic ions of acid dye is available in acidic solutions. The dye adsoption
kinetics and equilibrium isotherm of the composite foams were well described with the pseudo-second order kinetic model and
Langmuir isotherm model, respectively. The maximum adsorption capacity (q
max) for the PU/chitosan composite foams with 20 wt% chitosan content is evaluated to be ca. 30 mg/g. 相似文献
107.
In this study, biodegradable composites were prepared using cellulose nanowhiskers and poly(lactic acid). For processing at high temperature over 200 °C, cellulose nanowhiskers were prepared by ultra-sound treatment, with the high thermal stability of natural cellulose. The nanowhiskers were confirmed using transmission electron microscopy, X-ray diffraction, and thermo-gravimetric analysis. Surface modification of the cellulose nanowhiskers was performed to increase the adhesion between hydrophilic nanofillers and hydrophobic polymer matrix. The dynamic mechanical thermal analysis of the composites showed better reinforcing effect of the modified cellulose nanocrystals. The effects of cellulose nanowhiskers on the biodegradability of poly(lactic acid) were studied using a microbial oxidative degradation analyzer. 相似文献
108.
Lunder Mojca Roškar Irena Hošek Jan Štrukelj Borut 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(1):47-53
Plant Foods for Human Nutrition - The diet rich in fruits and vegetables reduces the risk of metabolic syndrome, including diabetes development by various mechanisms of action, mainly due to the... 相似文献
109.
Nguyen Phuong Thao Nguyen Xuan Cuong Bui Thi Thuy Luyen Tran Hong Quang Tran Thi Hong Hanh Sohyun Kim Young-Sang Koh Nguyen Hoai Nam Phan Van Kiem Chau Van Minh Young Ho Kim 《Marine drugs》2013,11(8):2917-2926
Inflammation is important in biomedical research, because it plays a key role in inflammatory diseases including rheumatoid arthritis and other forms of arthritis, diabetes, heart disease, irritable bowel syndrome, Alzheimer’s disease, Parkinson’s disease, allergies, asthma, and even cancer. In the present study, we describe the inhibitory effect of crude extracts and steroids isolated from the starfish Astropecten polyacanthus on pro-inflammatory cytokine (Interleukin-12 (IL-12) p40, interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α)) production in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs). Among those tested, compounds 5 and 7 showed potent inhibitory effects on the production of all three pro-inflammatory cytokines with IC50 values ranging from 1.82 ± 0.11 to 7.00 ± 0.16 μM. Potent inhibitory activities were also observed for compound 1 on the production of IL-12 p40 and IL-6 with values of 3.96 ± 0.12 and 4.07 ± 0.13 μM, respectively, and for compounds 3 and 4 on the production of IL-12 p40 with values of 6.55 ± 0.18 and 5.06 ± 0.16 μM, respectively. Moreover, compounds 2 (IC50 = 34.86 ± 0.31 μM) and 6 (IC50 = 79.05 ± 2.05 μM) exhibited moderate inhibitory effects on the production of IL-12 p40, whereas compounds 3 (IC50 = 22.80 ± 0.21 μM) and 4 (IC50 = 16.73 ± 0.25 μM) moderately inhibited the production of TNF-α and IL-6, respectively. 相似文献
110.
Doobyeong Chae Zahid Manzoor Sung Chun Kim Sohyun Kim Tae-Heon Oh Eun-Sook Yoo Hee-Kyoung Kang Jin-Won Hyun Nam Ho Lee Mi-Hee Ko Young-Sang Koh 《Marine drugs》2013,11(9):3272-3287
Sargassum muticum (S. muticum) is a brown edible alga and widely distributed in Korea. This report was designed to evaluate the anti-inflammatory properties of apo-9′-fucoxanthinone (APO-9′) isolated from S. muticum on pro-inflammatory cytokine production.
S. muticum extract (SME) exhibited significant inhibitory effects on pro-inflammatory cytokine production in bone marrow-derived macrophages (BMDMs) and dendritic cells (BMDCs). APO-9′ pre-treatment in the CpG DNA-stimulated BMDMs and BMDCs showed a strong dose-dependent inhibitory effect on interleukin (IL)-12 p40, IL-6 and tumor necrosis factor (TNF)-α production with IC50 values ranging from 5.31 to 13.79. It exhibited a strong inhibitory effect on the phosphorylation of ERK1/2 and on activator protein (AP)-1 reporter activity. APO-9′ pre-treatment exhibited significant inhibition of CpG DNA-induced production of inducible nitric oxide synthase. Taken together, these data suggest that SME and APO-9′ have a significant anti-inflammatory property and warrant further studies concerning the potentials of SME and APO-9′ for medicinal use. 相似文献